Explaining the anatomy of eye ball as per mbbs third year syllabus of opthalmology.

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2. Gross anatomy

3. The Eyeball
Each eyeball is a cystic structure kept distended
by the pressure inside it.
Eyeball is not sphere but ablate spheroid.
It has anterior and posterior curvature.
The maximal convexities of the these curvatures
of the eyeball are called the anterior and
posterior pole, respectively.

4. Dimensions of an adult eyeball
Anteroposterior diameter 24 mm
Horizontal diameter 23.5 mm
Vertical diameter 23 mm
Circumference 75 mm
Volume 6.5 ml
Weight 7 gm

5. Coats of the eyeball
Three coats: Outer (fibrous coat), Middle (vascular
coat) and Inner (nervous coat).
Fibrous coat
• Dense strong wall
• Protects the intraocular contents
• Anterior 1/6th transparent part is called cornea
• Posterior 5/6th opaque part is called sclera
• Junction of the cornea and sclera is called limbus
Vascular coat (uveal tissue)
• Supplies nutrition
• Consists of iris, ciliary body and choroid
Nervous coat (retina)
• Concerned with visual functions.

6. Segments of Eye ball
Anterior
Segment
Anterior
Chamber
Posterior
Chamber
Posterior
Segment

7. Anterior Segment
It includes crystalline lens( which is suspended from the ciliary body by zonules), and structures
anterior to it, viz., iris, cornea and two aqueous humour-filled spaces anterior and posterior
chambers.

8. Anterior Segment (…continued)
 Anterior chamber.
 Bounded anteriorly by the back of cornea,
 Bounded posteriorly by the iris and part of
ciliary body.
 About 2.5 mm deep in the centre in normal
adults.
 Shallower in hypermetropes and deeper in
myopes.
 Contains about 0.25 ml of the aqueous
humour.
 Posterior chamber
 Bounded anteriorly by the posterior surface of
iris and part of ciliary body
 Posteriorly by the crystalline lens and its
zonules

9. It includes the structures posterior to lens, viz., vitreous humour (a gel like material which fills
the space behind the lens), retina, choroid and optic disc.
Posterior Segment